Factor 4y^4 - 64

The first step to solve this expression is to factor out 4 from the expression
4( - 16)
Using the equation a² - b² = (a - b)(a + b), factor the expression in the parenthesis.
4(y² - 4) × (y² + 4)
Using the equation a² - b² = (a - b)(a + b), factor the expression in the first parenthesis to find your answer.
4(y - 2) × (y + 2) × (y² + 4) 
This means that the correct answer to your question is 4(y - 2) × (y + 2) × (y² + 4).
Let me know if you have any further questions
:)